Switch assembly



Sept. 25, 1945. J. N. GILMAN EAL 8 SWITCH ASSEMBLY Filed Dec. 16, 1940 2 Sheets-Sheet 1 INVENTORS. JAMES N. G'ILM/IN CHANDLER C. R088 A TTORNEY p 1945- J. N. GILMAN EI'AL 2,385,356

' swim; ASSEMBLY Filed Dec. 1a, 1940 2 Sheets-Sheet 2 INVENTORS. /AME$ 1v. GILMAN EIHANDLER a ROSS.

ATTORNEY UNITED STATES sWrTcH ASSEMBLY JamesNl Gilman, akland, and Chandler CLRoss, Alameda, Calif-L; said Ross assigrior to said Gilnian Application-December 16, 1940, SerialNo. 370,262 (01. 200 -83) Our improved switch has been designed for" use part'ieularly' in connection with the regulation of pressureinpump systems of the pressure type; a pump system of this character,- a pressure is developed in: the system by pumping the. Water into a pressure tank, against an air cushion, andmaintaining the air cushion pres-- sure -a;--preisleterm'ined range. When the pressure'therei-n falls below a minimumpressure value as resultsfromconsumption of the Water or reduction in air cushion volume, a pressureresponsive switch automatically goes into operatiolr and connects the pumpmotor in circuit; thus causing-the pump to' replenish thesupply of water to: the tank, to an ex-tent sufiicient to restore the pressure condition therein.

Switches of the mechanical contact type have been used and'are still used for this purpose. They have proven to be a source of continuai trouble,-for these switches; on the making and particularly the breaking of the circuit to thepumrrmet'or; are subjected to the high inductive load of'themotor windings, causing heavy arcing across the switch contacts, with resulting pitting thereof. Where the pressure tank has lost some or its aircushion; either through leakage of air from the tanhorabsorption of airby'the water; the pressure i'n'the system becomes more sensitive to consumption of the: waterin the tank, with the result that a more frequent operation of the switch occurs to maintain proper tankv pressure, evento the extent of sometimes connecting; and disconnecting. the motor at't'he rateoffou'r or five times a minute.- Under such conditions, excessive. heatingor contacts is apt to occur, wlth consequent increased. damage tothe switch; Whn it is considered that pump systerns of the pressure type embodying these switches areintended primarilyfor use in farmi'ng districts and rural communities,- usually remote-from any service, the desire for a trouble*- free switch-becomes-of major importance;

Eiltabletype switches incorporating mercury." tube: switch elements.- adapted for suchuse, exist; but weihave found: such switches asare avail-- able to-beeither inflexible: as tocurrent-capacity and,=-therefore, not'adaptable for awide range of" pump: systems: of varying capacity orare toocr i'tical in the" matter of 'install'at'ion; or some-- what too expensive "fbr production.

-Among the objects of" our invention; areto ill provide a novel and improved switch assembly em loyin a mercury tube-switch element (10 Whichmay' he c'onfirredwithin a reasonably small space and Yet be rugged lenditself to economical production,-

('2) Which may be altered in electrical curcarryi-hgi capacity; without altering: the switchassembly structure,- thereby rendering itself adaptable for use-in puin'p'systems ofdiirerent capacities,

3) Whichsliah be relatively insensitive to out of line pump installatib'ns within the tolerances permittedthe installation of such pumps,

(4) Whichshall maintain a-substahti'ally con;- star-it l'oadon the pressure side' of the pump-system in s'pite'o'fvariations in fihe'afi'g le of installaticnof themercurytube' switch element, and

(5) Which may' be conveniently locked 'against operation during servicing or repairing; of the pump s stem.

Additional objects of our invention will be brought out in the following description of the same taken inconjunction with the accompanying 'd'r'awings wherein I Figure is a" perspective View with a part of the casing broken away,- or a preferred form of our" switch assembly- Figures 2-a'nd-3 are'sid'e views with'a portion of the casing broken away-,1 showing the operation of a manuallycontrolled locliing feature,

Figure 4 is a viewg in' se'ctiont taken along the line 4 4- of- Figure 1;. c

Figure" 5 is a View, in section; taken along the lihe 5"''5 0f FiEiili 1 Figure 6 is-aplan"view of the switch assembly with the niercury tlibesvvit'ch element and sup'-' porting tameremoved,

Figure '7 is a View, in'- section; taken along-'- line 1-1 of Figure 1.-

In a general way', our iin'p'roved 'switch-involves a table or platforni" for supporting-I one or more switch elements; of 3 the mercury tube type; The table is pivotal-1y supported and adapted to be t'iltedthrough a substantial angle. Such tilting is directly; controlled by atoggle arrangement;

the

tion of one-of the toggle r'nernber's', po'sitionin turh'is controlled by the" pressure responsi'vemean's connectedtosuch" apparatus as it is StI'llCtlOl'l'iS suchthataswitchwhe'ii adj-unaware predetermined pressure range of operation at the factory; will adhere to-such adjust'm'enti in spite" of improper installation factorswhich m'ight oth erwis'e" serve to" alter the eirecuve "pressure range of the switch. Also, the construction will allow of a wide angle of tilt of the mercury tube switch elements, thereby rendering the switch substantially insensitive to out of line installations of apparatus on which such switches may be mounted.

More specifically, our invention, as depicted in our improved embodiment, comprises a switch assembly fitted into the lower half I of a casing 3 for which a cover 5 is provided. This lower half of the casing is formed with a circular indent l at its central portion, this indent in turn being provided with a transverse slot 9 therethrough;

A plunger H comprising a broad circular base l3 adapted to lie within the indent, and a pair of spaced upright elements i5 extending through the slot, and each terminating in a knife edge I1, is maintained in position by a comparatively loose diaphragm l9 spanning the indent and held in position by a diaphragm flange 2| which is bolted to the bottom of the casing. The diaphragm may be of any suitable material, but is preferably formed from material comprising a layer of fabric between and preferably united to layers of rubber.

The diaphragm flange is provided with a central opening to receive a pipe coupling 23, and this coupling in turn enables connection to some associated apparatus to which the switch is made responsive.

Within the casing 3 and surrounding the plunger H, is a frame including two side walls and an end wall 21, the side walls being pro-' vided with integral flanges 29 for attachment to the floor of the casing. A plunger table 3| lying between the side walls 25 of the frame, is hinged to the rear wall 21, by extending through a slot 33 in the rear wall and having its edge 35 turned up. At an intermediate point, the plunger table is provided with an inverted V-indent 31 to receive the sharp edges of the plunger H and enable the table 3| to fulcrum thereon.

A continual pressure in a direction opposing any lifting force which might be exerted by the plunger against the plunger table, is applied against the free end of the table by a spring 39 whose purpose is to determine the operating range of pressures of the switch. This spring is supported between two cupped washers RI and 43 about a bolt 45 fastened on end to the bottom of the casing and .extending upwardly through. a hole 46 in the plunger table. The lower washer 43 is formed with an inverted V-indent 41 to receive a complementary indent 49 formed in the end of the plunger table. A nut 5i threaded to the upper end of the spring supporting bolt 45, provides for adjusting the spring pressure, thereby enabling adjustment in the range values of the spring.

The plunger table 3! at its free end, is formed with an ofiset 53. This ofiset is provided with an opening 55 -to permit passage of a bolt 51 therethrough, which is also mounted on end to the bottom of the casing. This bolt is of reduced cross-section at its upper portion, beginning a slight distance from the lowermost position of the plunger table, that is, the position of the plunger table when the plunger is exerting no upward pressure against the same. A cupped washer 59 is carried on the shoulder formed by the reduced section, and this forms a mounting for a differential spring 6|, the compression of which may be varied by means of a threaded cup shaped nut 63.

v Pivotally connected to the side walls 23 of frame, is a table 65 for supporting or carrying one or more switch elements 61 of the mercury tube type. This table comprises a flat supporting surface 68 overhanging the front edges of the walls 25,and depending side walls or flanges 69, these depending walls being pivotally connected between the side walls 25 of the frame by a pivot shaft H. The edges of the depending walls 69 facing the springs 39 and GI, are provided with rather large square-shaped notches 13.

The plunger table 3| is formed with a shallow depending flange 15 at each side thereof, carrying between them a shaft ll to which a roller arm 19 is pivoted, which arm extends upwardly through an opening 8| in the plunger table, provided for the purpose. This roller arm is of U-shaped channel construction, and carries between its upper ends, a roller 83, preferably of case hardened material.

A roller shaft extending through the notches 13 formed in the edges of the side walls 69, connects the side walls 25 of the frame. This shaft, through its cooperation with the sides of' the notches, acts as a stop in determining the permissible angle of throw of the switch element supporting table 65. This same shaft also serves as a pivot shaft for a link 81 positioned thereon midway between the depending walls 69 of the table 65. This link is formed with a V-shaped end 89 facing the roller, and is bifurcated at its other end to frictionally straddle a rod 9| joining the depending side walls 69 of the table 65. A rather stiff spring 93 encircling the roller arm pivot shaft 11, and having one end braced against the underside of the plunger table 31, and at its other end bearing against the roller arm 19, serves to maintain the roller 83 in contact with the V-end of the link 81 and with sufficient pressure to tilt the table in either of two directions, depending upon the particular position of the roller 83 with respect to the V-end of the link.

To support a switch tube upon the table, we employ a standard type of spring clip 95, but we mount this clip to the table 65 in such a way that the mounting axis thereof is substantially normal to the axis of tilting of the table, or in other words, substantially normal to the shaft H about which the table pivots or tilts, and is so directed as to hold the mercury tube switch element 61 with its axis lying in a direction normal to both the mounting axis of the clip and the axis of tilting of the table. This has for its effect to provide a rather stable arrangement and one in which the inertia imparted to the switch tube during tilting, will not tend to turn the clip on its mounting axis and thereby efiect'a loosening thereof.

Against one end wall of the casing, we mount a terminal block 91 having four terminals carried thereon. Theseare identified as L1, L2, M2 and M1 to indicate line connections to power lines and motor respectively, these connections being brought into the switch casing through suitable openings in the walls of the bottom half I. A jumper 99 connects the two intermediate terminals L2 and M2. The mercury tube switch element 6! is connected by leads [0| to the terminals L1 and M1 and when more than one mercury tube switch element is required to increase the current carrying capacity of the switch assembly, it will be connected in parallel with the other. It will be'noted that the line connections and motor connections are always below the leads IOI;

connecting the mercury tube elements 6] to the terminal block, andtbis at, all times recludes the mercury tu e connections. from ever becoming enan led with the other wires.

In the operation of, the switch assembly and i the abs n e of a y pressure existin in the co plin 2 th un er tablet! w l beheld at its l wermost os tion by the s in 39, thereby ositionin the roller 13 to bear a ainst: the. lower slop o the i-eud oi the link; 81- 'Ibis in turn will cau e the table 65, to, be tilted 51 91. add-- rest-io as to. c os the ci cuit Whenth mercury tube element $1 is moun ed. as indicated loath d awings By r versin this element. one can b ain an o nin Oi a cir ui nder the; some. nd t ons- An in rease in. pressure in the couclin t a value sufiicient to overcome .tbe'com ressi n. o th ra e spr ng 33. and. ultimat ly th ombined compressivev force of. oth, springs as and 6 will cause the plun er to. move up.- wardly and lift the plun e tab e 31. which, n turn w ll arry with it, the rolle arm 19; audits roll r 3- When the ro ers th s lift d sumi ntly to pa s the po nt of th v end, the res: sure exerted by he rollerarm. p in all wi l be sufiicient to tilt the tabla a reverse direction 2 and break the ircuit. he. extent f swine-l as previously indicated, will be determined by the width of the notches 13 in the edges of the depending walls 69..

The switch assembly, in an actualinstallation, is usually mounted vertically (that i With the floor of the casing substantially horizontal) on apparatus with which it is to. be used. In

the matter of a pressure system installation, it

will be mounted on the pump apparatus, which is usually installed at some distance. from the actual point of consumption of the water. prior installations, when it became desirable to service the pumping apparatus, it was. necessary to shut on" the electric power at; the house or some other point remote from the installation, and this, from the ser icemenfs viewpo n on.- stitute a decided n o ni e. o a e c g job generally required a repeated; connecting and shutting old oftlae power to the pump. motor be-. forea job could be considered complete, y

In our switch as embly, we h ve ncorpo at d a feature which Will enable aser-viceman tomanually tilt the mercury tube switch element to its circuit opening position and locking the sameas long as necessary, and which will permit releasing or unlocking of the mercury tubeelement when desired, for putting-- the apparatus back into;

operation. Thus, without leaving the job, he can efiectively disconnect the motor from the electric circuit, as and when the work, requires Toac complish this, We provide a bushing l- 3 in the front end wall of the lower half of the casing, and in this we rotatably mount a. rod L05. That end. of the rod, protruding from the casing, is bent to provide a, handle l 0.1, while the end. portion of the rod, within the casing, is bent to a, double right angle bend to form alateral offset I09 adjacent the front edge of one, of the side walls of the frame. A compression spring l ll surrounding part of the rod within the casing, is fixed to the rod at one point, as by having one of its ends extending into an opening formed therein, while at its other end, the spring bears against the interior face ofthe bushing"! 03. Upon rotating the rod, the ofi'set portion Hi9 within the casing may be raised into engagement with the upper edge. ofone of the notches 1-3, to tilt the mercury tube switch supporting table 65'from one position determining a closed circuit; to its other flied by the manufacturer of 3 position determining an open circuit. As soon as the manually rotatable rod 405, or more particularly, the offset portion 199, thereof, rises above the upper edge of that. frame side wall 25 with which it, engages, the compression spring I goes into action, forcing this offset portion along the upper edge of the side Wall and into the associated notch '13, thereafter precluding the supporting table from returning to its circuit closing position. To restore the table to its previous circuit closing position, the offset portion of the rod is withdrawn against the action of the spring ill, by, pullin on the handle I01, and then turning the handle so as to swing the ofiset. portion downs wardly and into permitted front, edge of the side wall 25.

Switches for use in controlling the pressure pump systems, are usually adjusted for a particular pressure range, at. the factory. Upon in-. stalling the pump apparatus, it quite frequently happens that any deviation beyond permissible tolerance in the installation of the pump apparatus, will often change the pressure characteristics of the switch, from what, they were adjusted to be, prior to the installation. This necessitates, onv the part of theserviceman or installing enineer, a critical readjustment of the switch, following, installation of the system.

A particular advantage in the construction of our improved switch assembly, resides in the fact that it is substantially insensitive to any such variations occurring in installation of the pump apparatus. This. may be attributed to the fact that, although any such variations may unbalance the switch apparatus to. the extent of alterin the amountv of work necessary to tilt. the mercury tube switch element, such change in work necessary to accomplish, such tilting'is not reflected back to the pressure side of the pump system, but is taken up entirely by the roller arm spring 93 which constitutes, in effect, a source of energy independent of the pressure energy derived fromv the pump system. In our improved switch assembly, therefore, the energy derived with respect to a vertical axis. Consequently, once the springs 39 and BI in the switch assembly are adjusted to impart predetermined pressure characteristics to the switch assembly, such adjustment will hold, even though the pump apparatus on which the switch assembly is mounted, may have been installed at a greater angle to the vertical axis, than is normally considered permissible.

Another and very important advantage arising out of the switch assembly described-byus, is that it enables us to swing the mercury tube switch element through an angle greater than that Specthe mercury tube switch, and to an extent greater than the permissible angle of deviation from the normal; permittedin the installation of the pumping apparatus or other apparatus on which the switch is mounted. This permits of a greater tolerance in the installed position of the switcnassembly, than is permitted in thepump apparatus, and

assures one thatso long as the pump apparatus engagement with the is installed within the limits of tolerance specified by the manufacturer, the switch assembly will always be in proper operating condition, without any apparent change in the effective pressure characteristics thereof as predetermined at the factory. In as much as the angle of tilting is a function of the size of the notches 13, these can readily be altered to adapt the switch to mercury tube switch elements of different requirements, without detriment to the advantages attributed to the switch assembly.

The utilization of an independent spring as a source of energy for tilting thetube supporting table assures one of a rapid tilting action, regardless of the slowness with which the rest of the switch assembly might operate. This coupled with the wide tilting angle, characteristic of our switch, means a rapid break in contact within the mercury tube element with less chance of establishment of an are through kick-back on the part of the mercury in the tube.

The table, which supports the mercury tube switch elements, has an additional function in our switch, besides those already discussed. It is noted that this element practically covers the inner workings of the switch, and consequently, when the casing cover is removed for any reason, the table serves to protect the inner workings of the switch assembly from dirt or damage,

While we have disclosed our invention in considerable detail, it is apparent that the same is subject to modification and change, without departing from the spirit thereof, and we accordingly do not desire to be limited in our protection to the specific details disclosed and described, except as may be necessitated by the prior art and the appended claims.

We claim:

1. A switch assembly comprising a table; a clip afiixed to one side of said table with its mounting axis normal to the surface of said table; means for pivotally supporting said table in a receptacle, on an axis normal to the mounting axis of said clip and with the clip side of said table facing an open side of said receptacle; independent pressure means associated with said table and disposed in said receptacle to permit access to said clip through said open side of the receptacle, said means being capable, when in one position, of imparting angular movement in one direction to said table, and capable when in another position, of imparting angular movement thereto in a reverse direction; means for shifting said pressure means between such positions in accordance with conditions apt to exist in apparatus to be controlled by said switch assembly; and a cover enclosing the open side of said receptacle.

2. In a switch assembly; a casing; a pressure responsive plunger supported at the bottom of said casing; a toggle frame comprising a pair of side walls and an end wall surrounding said plunger; a plunger table hinged to said frame end wall and extending between and bey-ondsaid side walls, said plunger table being fulcrumed at an intermediate point upon said plunger, enabling said table to be raised by said plunger in response to a lifting of said plunger; spring means bearing against said table with a predetermined pressure and in a direction opposing the lifting of said table by said plunger; a mercury tube switch element supporting table; means for pivotally securing said table to the side walls of said frame; means associated with said switch element supporting table and frame for permitting an angular movement of said table between definite limits; and toggle means operating from said plunger table in response to said pressure responsive plunger, for tilting said switch element supporting table between said limits.

3. In' a switch assembly; a casing; a pressure responsive plunger supported at the bottom of said casing; a toggle frame surrounding said plunger; a plunger table hinged to said frame, said plunger table being fulcrumed at an intermediate point upon said plunger, enabling said plunger table to be raised by said plunger in response to a lifting of said plunger; spring means bearing against said table with a predetermined pressure and in a direction opposing the lifting of said table by said plunger; a tiltable mercury tube switch element supporting table pivotally secured to said frame; toggle means including a toggle link within said frame having a V-shaped end, and disposed with its opposite end in tilting engagement with said switch element supporting table, and a roller arm pivotally secured to said plunger table between said compression spring and said plunger, a roller carried by said arm, and spring means continually urging said arm toward said toggle link to maintain said roller in constant engagement with the V-end thereof.

4. In a switch assembly; a casing; a pressure responsive plunger supported at the bottom of said casing; a frame comprising a pair of side walls and an end wall surrounding said plunger; a plunger table hinged to said frame end wall and extending between and beyond said side walls, said plunger table being fulcrumed at an intermediate point upon said plunger enabling said plunger table to be raised by said plunger in response to a lifting of said plunger; spring means bearing against said table with a predetermined pressure and in a direction opposing the lifting of said table by said plunger; a tiltable mercury tube switch element supporting table having depending side flanges for pivotally securing said table to the side walls of said frame; a rod joining said side flanges, each of which is notched adjacent the open side of said frame; a link within said frame having a V-shaped end facing the open side thereof and a bifurcated end in straddling engagement with said rod; a shaft through said link and the notches in the ends of said side flanges and connecting the side walls of said frame to constitute both a pivot shaft for said link and stop means for fixing the angular throw of said tiltable table; a roller arm pivotally secured to said plunger table between said compression spring and said plunger; a roller carried by said arm; and spring means continually urging said arm toward said link to maintain said roller in constant engagement with theV-end thereof.

5. In a switch assembly; a casing; a pressure responsive plunger supported at the bottom of saidcasing; a toggle frame comprising a pair of side Walls and an end wall surrounding said plunger; a plunger table hinged to said frame end wall and extending between and beyond said side walls, said plunger table being fulcrumed at an intermediate point upon said plunger enabling said table to be raised by said plunger in response to a lifting of said plunger; spring means bearing against said table with a predetermined pressure and in a direction opposing the lifting of said table by said plunger; a tiltable mercury tube switch element supporting table having depending side flanges for pivotally securing said table to the side walls of said frame; a rod joining said side flanges, each of which is notched adjacent the open side of said frame; a toggle link within said frame having a V-shaped end facing the open side thereof and a bifurcated end in straddling engagement with said rod; a shaft through said link and the notches in the ends of said side flanges and connecting the side walls of said frame to constitute both a pivot shaft for said link and stop means for fixing the angular throw of said tiltable table; a roller arm pivotally secured to said plunger table between said compression 10 spring and said plunger; a roller carried by said arm; spring means continually urging said arm toward said toggle link to maintain said roller in constant engagement with the V-end thereof; and manual control means for locking said tiltable switch element supporting table in an open circuit determining position.

JAMES N. GILMAN. CHANDLER C. ROSS. 

